Qliphoth

According to Xbox E3 Live Interview, the demon tree  is the crux of the story of Devil May Cry 5. It appears on Red Grave City and with it,

a demonic invasion began.

According to V, the Qliphoth is a tree that existed before the birth of the Underworld itself and grows fruit that imbues a demon with divine power. It thrives on human blood, and those whose blood it sucks "...don't turn out too well."

Trivia
The Qliphoth is the representation of evil or impure spiritual forces in the Kabbalah, an esoteric discipline and school of thought in Judaism. They are the opposite of the Sefirot that represent the ten emanations and attributes of God in which he sustains the existence of the universe.